The present invention relates generally to portable electrical humidifiers, and more specifically to those known as impeller or "cool mist" type humidifiers, which employ a fan blade, a spinning suction tube, and a diffuser screen. Mist is created mechanically through collision of water dispersed by the spinning tube against the diffuser screen and is exhausted after mixing with air by the fan blade.
Impeller humidifiers have been known for many years and it is common to employ therewith a suction tube which is attached directly at its top end to the fan blade which also serves as a cover. Since the tube is generally a hollow cone with its apex pointing downwardly into a water filled reservoir and having only one small intake hole and no more than a few exhaust holes, it is practical to manufacture the tube with an open ended top and to cover the open end with the fan blade. Mating of the tube to the fan blade must be substantially sealed to avoid unintended dispersal of water at that junction. Accordingly, the tube generally is glued, welded, or screwed to the fan blade.
The drawing of water upward into the tube against gravity requires that the cross sectional area of the intake opening be minimized. Thus, the intake opening typically is only large enough to allow an adequate water flow for an acceptable humidification rate. However, the intake cannot be so small as to become easily blocked by particles or the build-up of impurities from the water and generally is on the order of 0.060" to 0.187" in diameter.
The exhaust openings adjacent to the upper end of the tube should also be small tangentially to avoid structural weakening of the tube. Usually the tube protrudes precariously from the humidification head when removed from the reservoir and its long thin profile renders it easily broken if not adequately strong. The exhaust openings should also be small enough in the vertical direction to ensure that water sprayed therefrom can be properly directed toward the diffuser screen. If the spray is too wide and a portion is thereby aimed away from the screen, it will not collide with the screen to become mist but will instead return to the reservoir, resulting in inadequate humidification efficiency. Exhaust openings are generally in the order of 0.060" wide vertically and 0.060" to 0.50" wide tangentially.
The reservoirs of these humidifiers are most often filled with water taken directly from a tap. Such water is often laden with impurities and minerals. Also, when water is left unused in the reservoir for an extended period, microbial growth may occur. These impurities and growth become a problem for the operation of the humidifier when they are drawn into and block the intake opening or when they build-up or grow within the suction tube, impeding the tube's ability to draw water to the exhaust openings. It is therefore critical for effective longterm performance that the intake opening hole and inner surface of the suction tube be cleaned regularly.
Present impeller humidifiers have several drawbacks which prevent simple and safe cleaning of the tubes. First, if the tube is permanently attached to the fan blade, rinsing the tube under running water risks the possibility of dangerously wetting the electrical components within the humidification unit. Second, because the intake and exhaust openings are so small, it is difficult to impossible to access the inner surfaces of the tube in order to perform an adequate cleaning. In those humidifiers having the tube attached to the fan blade by screws, a screwdriver is required to disassemble the tube from the fan blade and access those inner surfaces. As a result of these difficulties, it is often the case that the cleaning required for proper longterm performance is compromised or neglected. To alleviate these problems, one prior impeller humidifier employs a collar that detachably secures a tube to a fan blade. However, the collar increases cost and complicates cleaning. In addition, removal of the tube and collar undesirably exposes electrical portions of the humidification unit.
It is the object of the present invention therefore, to provide a humidifier with a suction tube that is easily removed and cleaned.